September 10: ORD

Today is September 10th. It's the 253rd day of the year. 112 days remain. It's week 37 of the year.

Unless noted, the following data is based upon observations collected by the National Weather Service, Chicago, at O'Hare International Airport (ORD) between November 1978 and last year. ORD has been the official site of record for Chicago since Thursday, January 17, 1980.

According to the National Climatic Data Center (NCDC), the normal high is 76 and the normal low is 56. I've calculated the 31-year averages at 79 and 58.

On the hot side, in 1983 the high was the record high of 95 with a low of 67. In 1986 the high was 90 with a low of 70. In 2005 the high was 92 with a low of 67. In 2000 the high was 84 with a low of 72. Another warm high was 89 in 2002. The record warmest low of 75 occurred way back in 1912, a time when the thermometer was located on the lakefront. Over the last 31 years, 23 highs (74%) were: 70s (10) and 80s (13). Three highs were in the warmer 90s and five were in the cooler 60s. In 1996, today was the last day of a high in the 80s, the earliest day of the last 31 years.

In looking back through the years to the first September at O'Hare in 1959, the following instances were notable: in 1978 the high was a hot 92 with a low of 65, a hot day. In 1972 the high was a cool 64. In 1971 the high was 87 with a warm low of 69, a hot day. In 1968 the high was a cool 61 with a low of 55, a six degree spread. In 1966 the high was 84 with a low of 47, a 37 degree spread. In 1964 the high was a hot 93 with a low of 65, a hot day. In 1961 the high was a hot 89 with a low of 67, a hot day.

More recently, there was a large spread of 36 degrees in 1988 (86/50) and a small spread of four degrees in 2006 (64/60).

On the cool side, there were no days of a mean of at least 11.5 degrees below normal. In 1995 the high was 64 with a low of 46. That high of 64 shares the 64 degree high in 2006 as the coolest highs. That low of 46 was the coolest low. In 1993 the high was 65 with a low of 47, just a degree warmer than 1995. The record low of 44 was set in 1943. The record coolest high of 53 occurred way back in 1917, a time when the thermometer was located on the lakefront. Over the last 31 years, 24 lows (77%) were: 50s (10) and 60s (14). Five lows were in the cooler 40s and two were in the warmer 70s.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 6:00 and sunrise is at 6:28. Sunset is at 19:12 and twilight ends at 19:40. There's a total of 12 hours, 44 minutes of daylight today and 13 hours, 40 minutes between twilights. We are losing two or three minutes of daylight a day. Tomorrow twilight begins at 6:01 and sunrise is at 6:29. The moon is waxing crescent, having passed the new phase two days ago at 5:30 in the morning. Illumination was 5% at midnight, will be 8% at noon and 12% at midnight tonight. Moonrise is at 9:20 this morning. Moonset is at 20:05 tonight and moonrise is at 10:36 tomorrow morning. Moonlight time is 10 hours, 45 minutes which is 46 minutes shorter than yesterday.

Patriot Day is tomorrow and Grandparent's Day is in two days. -Bernie-